ForkUnion: Low-latency NUMA-aware fork-join thread-pool with zero allocations, syscalls, CAS, or false-sharing on the hot path for C, C++, Rust, and Zig

ForkUnion is a NUMA-aware fork-join thread-pool for systems languages, built for the tightest parallel-for loops rather than task queues. Its dispatch hot path makes no heap allocations, no system calls, and no compare-and-swap operations, and shares no cache line between workers, so fork-join latency stays flat as cores and sockets multiply. Idle workers park on a hardware address monitor where the processor offers one, waking the instant a peer writes the watched cache line, while per-domain memory placement and private per-worker cursors keep synchronization off the interconnect.